The present invention relates generally to active phased array radars, and more particularly, to an RF transmit drive leveling adjustment method using transmit amplitude adjustment range measurements for use with active phased array antennas.
Maintaining RF drive levels of active phased array radars identical to those used during calibration measurements is necessary to minimize residual errors of active array element phase and amplitude control. This correct RF drive level corresponds to a transmit gain compression point at which transmit calibration measurements were initially made. Conventional array transmit RF drive level control considerations are based on maintaining absolute power levels. These absolute power measurements have typically been required for all array transmit calibration measurements, and during array transmit operation. This technique allows for the use of a relative, versus an absolute, measure of transmit RF drive.
Extending the useful range of command linearization tables by adjusting transmit RF drive levels can save considerable calibration resources associated with adjustment over a variety of radar waveforms. The amount of memory savings depends on the antenna sidelobe requirements, the range of required radar mode waveforms and the number of command linearization tables for a given array antenna. The savings will occur due to a reduction in the cost of the electronic hardware, and also in terms of array test time, associated data processing and subsequent verification.
Accordingly, it is an objective of the present invention to provide for an RF transmit drive leveling adjustment method using transmit amplitude adjustment range measurements for use with active phased array antennas. It is a further objective of the present invention to provide for an RF transmit drive leveling adjustment method that extends the useful range of command linearization tables used in active phased array radars.